1. Technical Field
The present invention relates to novel esters derived from alkanolamines, dicarboxylic acids and fatty alcohols, and to the cationic surfactants obtainable therefrom, as well as to their use as softening agents for natural and synthetic fibres.
2. Prior Art
Cationic surfactants derived from amines have been used widely for some decades as softening and conditioning agents for natural and synthetic fibres of all types, and are used in fields such as the treatment of textile fibres and of paper and in hair hygiene products.
For ecological reasons, owing to their greater biodegradability, the use of cationic amine derivatives in which the hydrophobic hydrocarbon chains are interrupted by functional ester groups has been usual for several years, those used mostly being the quaternized derivatives of polyalkanolamine esters, generally known as esterquats, amongst which one of the types used most is esterquats derived from triethanolamine, owing to their lower cost.
It is also well known that the above-mentioned esterquats are prepared from alkanolamine esters, produced previously by an esterification reaction of the alkanolamine with fatty acids or functionalized reactive derivatives thereof, by their quaternization with alkylation agents such as alkyl halides or sulphates. There is an abundant bibliography on the subject, amongst which patents or patent applications FR-A-1593921, EP-A-239910, EP-A-295385, WO-A-9101295, DE-C-19539846 and WO-A-9849132, amongst many others, may be mentioned.
However, it is well known that esterquats are less effective softeners than their homologues which do not contain ester groups, and this has led to various technical developments directed towards improving the softening efficacy of these esterquats.
Thus, patent U.S. Pat. No. 5,593,614 describes the improvement of the softening effect of esterquats by mixing them with non-ionic surfactants, patent U.S. Pat. No. 5,501,806 proposes the mixing of esterquats with other cationic surfactants, and patent application EP-A-394133 describes the use of acrylic cationic polymers as additives for improving softness.
British patent GB-602048 describes oligomeric alkanolamine esters based on the esterification reaction of triethanolamine with dicarboxylic acids and fatty acids, as well as their quaternization with methyl chloride or dimethyl sulphate and their use as softening agents for natural and synthetic fibres, and patents U.S. Pat. No. 4,719,382 and U.S. Pat. No. 4,237,016 describe the use of the esterquats described in the above-mentioned British patent, amongst cationic polymers of many other types, as additives for improving the softening efficacy of cationic surfactants which do not contain ester groups. Moreover, patent application WO-A-9812293 describes the use of the same oligomeric esterquats as additives for incorporation in the aqueous phase of softening compositions which contain esterquats, with the object of improving their softening efficacy.
German patent DE-C-19539846 describes the synthesis of esterquats derived from dicarboxylic acids, fatty acids and triethanolamine and their use as hair conditioners, and patent DE-C-19715835 describes esterquats based on the reaction of methyl diethanolamine and mixtures of fatty acids and dicarboxylic acids, with subsequent ethoxylation and/or quaternization.
Patent WO-A-9849132 describes the synthesis of esterquats derived from dicarboxylic acid/fatty acid/triethanolamine, within a specific selected range of proportions, and their use in fabric-softening compositions.
Lastly, patent DE-C-19519876 describes esterquats based on the reaction of a trialkanolamine with mixtures of fatty acids, dicarboxylic acids, and sorbitol and the subsequent quaternization and/or ethoxylation of the esters produced.
However, as far as the authors of the present invention know, the prior art always relates to alkanolamine esters and to their corresponding esterquats in which the hydrophobic chains result directly and mainly from the esterification of fatty acids, so that no descriptions have been found of alkanolamine esters and their corresponding esterquats in which the hydrophobic chains result mainly from fatty alcohols combined with the cationic portion of the molecule by means of a dicarboxylic-acid bridge and which, moreover, have a high degree of biodegradability and a greater softening efficacy than that of conventional esterquats.
The subject of the present invention is novel esters derived from alkanolamines, dicarboxylic acids and fatty alcohols, and the cationic surfactants obtainable therefrom.
Also included within the subject of the present invention is the use of the cationic surfactants based on the said esters derived from alkanolamines, dicarboxylic acids and fatty alcohols, particularly the esterquats obtainable therefrom, as conditioning and softening agents for natural and synthetic fibres.
Also included within the subject of the present invention are aqueous softening compositions for textile fibres containing, either as the active ingredient or as an additive for improving softening efficacy, cationic surfactants based on the said esters derived from alkanolamines, dicarboxylic acids and fatty alcohols, particularly the esterquats obtainable therefrom.
The alkanolamine esters of the invention are obtained by the esterification reaction of an alkanolamine of general formula (I) 
with a dicarboxylic acid or with a reactive derivative thereof, of general formula (II)
HOOCxe2x80x94R4xe2x80x94COOHxe2x80x83xe2x80x83(II)
and with a fatty alcohol, optionally alkoxylated, of general formula (III) 
in which formulae R1 is hydrogen, a C1-C6 alkyl group, or the residue 
R2 is a C1-C6 alkylene group, R3 is hydrogen or methyl, n is 0 or a whole number between 1 and 20, R4 is a C1-C36 alkylene group, optionally substituted or unsaturated, or an arylene group, and R5 is a linear or branched C2-C22 alkyl or alkenyl group.
Optionally, a fatty acid of general formula (IV) may also be incorporated in the reaction mixture
R6xe2x80x94COOHxe2x80x83xe2x80x83(IV)
in which R6 is a linear or branched C6-C23 alkyl or alkenyl group, an alkyl ester, a glyceride of the fatty acid, and/or a polyol, optionally alkoxylated.
The invention provides a cationic surfactant obtainable by the formation of the addition salt of the alkanolamine ester as above defined with mineral or organic acids.
The invention provides an esterquat obtainable by quaternization of the alkanolamine ester as above defined by the reaction with alkylation agents.
The invention besides provides a method of treating softening and/or conditioning treatment of natural or synthetic fiber, textile, paper fiber or hair fiber with the esterquats as above defined.
The invention further provides an aqueous fabric-softening composition which comprises:
(a) a surfactant or an esterquat thereof as above shown,
(b) one or a plurality of cationic surfactants active as fabric softeners,
(c) one or a plurality of non-ionic fabric-conditioning surfactants, in which the total amount of components (a), (b) and (c) is between 2% and 60% by weight in a manner such that, with respect to the total amount of the said components (a), (b) and (c),
(i) the proportion by weight of component (a) is between 2% and 99%,
(ii) the proportion by weight of component (b) is between 0% and 98%,
(iii) the proportion by weight of component (c) is between 0% and 40%, and
(iv) the proportion by weight of the total amount of (b) and (c) is between 1% and98%.
It is preferable that that the total amount of components (a), (b) and (c) is between 3% and 40% by weight,
(i) the proportion by weight of component (a) is between 3% and 80%,
(ii) the proportion by weight of component (b) is between 0% and 97%,
(iii) the proportion by weight of component (c) is between 0% and 30%, and
(iv) the proportion by weight of the total amount of (b) and (c) is between 20% and 97%.
The following may be mentioned as examples of alkanolamines which may be used: triethanolamine, N-methyl diethanolamine, N-methyl diisopropanolamine and triisopropanolamine, optionally alkoxylated with ethylene oxide or propylene oxide, or mixtures thereof, the non-alkoxylated alkanolamines, particularly triethanolamine, being preferred.
As examples of dicarboxylic acids, without intending to provide an exhaustive list, it is possible to mention succinic, malic, glutaric, adipic, sebacic, pimelic, suberic, maleic and terephthalic acids and also those known as dimers of fatty acids or dimeric fatty acids, which are produced by thermal oligomerization of unsaturated fatty acids, such as those marketed by Unichema International under the name PRIPOL7, for example, PRIPOL7 1009, or mixtures of the said acids. Adipic acid is preferred.
The fatty alcohols of formula (III), optionally alkoxylated with ethylene oxide or propylene oxide, may be hydrogenated or non hydrogenated fatty alcohols obtained from fats and oils of natural origin, for example, from tallow, palm, olive, coconut, sunflower, soya, grape marc or rape etc., non-alkoxylated alcohols which contain mainly between 16 and 18 carbon atoms being preferred.
Examples of fatty acids which may optionally be included in the esterification reaction are those obtained from vegetable and animal oils and fats such as those obtained from coconut, tallow, palm, sunflower, soya, olein, oil greaves, etc., optionally wholly or partially hydrogenated, as well as purified or synthetic fatty acids such as lauric, stearic, palmitic, oleic, linoleic, and 2-ethylhexanoic acids, etc.
The polyols which may also optionally be included in the esterification reaction may be, for example, glycerol, pentaerythritol, sucrose, glucose, sorbitol, or glycols such as ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, etc.
Advantageously, for the purposes of the present invention:
X the molar ratio of the dicarboxylic acid to the alkanolamine is between 0.2 and 1.2, preferably between 0.3 and 0.9, most preferably between 0.4 and 0.8,
X the molar ratio of the sum of the fatty alcohol and the fatty acid to the alkanolamine is between 0.2 and 2.0, and
X the molar ratio of the fatty acid to the fatty alcohol is between 0 and 10, preferably between 0.1 and 5.0, most preferably between 0.5 and 1.0.
X The esterification reaction is performed by methods known per se, such as that described in patent application WO-A-9849132 which is incorporated herein by reference.
The esterification reaction is preferably performed by condensation of the dicarboxylic acid, and optionally the fatty acid, with a mixture of the alkanolamine and the fatty alcohol, and optionally the polyol, at a temperature of between 120EC and 220EC, for a period of from 2 to 10 hours, preferably at a reduced pressure of about 5 to 200 mbar and in the presence of some of the catalysts already known for the esterification of conventional esterquats, for example, hypophosphorous acid and paratoluene sulphonic acid, and also in the presence of some of the usual stabilizers and antioxidants such as tocopherols, BHT, BHA, citric acid, etc. The esterification reaction can also be performed by condensing the dicarboxylic acid with the triethanolamine in the first place and adding the fatty alcohol afterwards.
It will be clear to a person skilled in the art that the esterification reaction may alternatively also be performed by other conventional techniques starting with reactive derivatives of the dicarboxylic acids, for example, their esters, their anhydrides, or their acid chlorides.
The esters thus produced are useful for preparing cationic surfactants efficacious for use in the softening and conditioning treatment of natural and synthetic fibres such as textiles, paper and hair. The cationic surfactants may be the esterquats obtainable by their quaternization with alkylation agents, or addition salts of the alkanolamine esters of the invention with mineral or organic acids such as hydrochloric, sulphuric, phosphoric, citric, and lactic acids, etc. The esterquats are preferred as cationic fibre-softening surfactants.
The esterquats are produced from the alkanolamine esters of the invention by an additional quaternization reaction, also known per se, for example, as described in the above-mentioned patent application WO-A-9849132.
For example, the reaction mixture resulting from the esterification is reacted with alkylating products such as methyl chloride, methyl bromide, dimethyl sulphate, diethyl sulphate, dimethyl carbonate, etc., preferably in the presence of organic solvents which facilitate the handling thereof, such as isopropanol, ethanol, propylene glycol, ethylene glycol, dipropylene glycol, fatty alcohols, etc., and the pH is subsequently adjusted to between 1.5 and 7.0, preferably between 2 and 4.5 by the addition of an acid such as any of hydrochloric, sulphuric, phosphoric, citric acids, etc.
The cationic surfactants obtainable from the alkanolamine esters of the invention exhibit a high degree of fibre-softening efficacy and, moreover, owing to their degree of biodegradability, are very well tolerated from the ecological point of view. Moreover, even if the said surfactants are not used in a major or predominant proportion, they considerably improve the softening efficacy of compositions based on conventional esterquats and other cationic surfactants and, when used as fabric softeners, counteract the adverse effect of the presence of anionic surfactant residues in the textile fibres after washing and during the rinsing stage.
In summary, the cationic surfactants obtainable from the alkanolamine esters of the invention may be used as the basic substance of fabric softening or hair conditioning compositions and also as additives for softening compositions or detergents the main active component of which is another cationic surfactant, or a mixture therefrom. As well as improving the feel of the fabric, its use in fabric-softening formulations facilitates ironing and reduces the appearance of creases during washing and its use in hair-conditioning compositions or as an additive in shampoos improves combability and the appearance of the hair.
With some of the products defined in this patent, particularly those in which the fatty chains have unsaturated bonds, it is possible to produce softening formulations which are translucent or transparent without the need to use the solvents usually used for formulas of this type.
In particular, although not exclusively, the present invention includes aqueous fabric-softening compositions which contain:
(a) cationic surfactants or esterquats obtainable from the alkanolamine esters of the invention,
(b) one or a plurality of cationic surfactants active as fabric softeners,
(c) one or a plurality of non-ionic fabric-conditioning surfactants, in which the total amount of components (a), (b) and (c) is between 2% and 60% by weight, in a manner such that, with respect to the total amount of the said components (a), (b) and (c),
(i) the proportion by weight of component (a) is between 2% and 100%,
(ii) the proportion by weight of component (b) is between 0% and 98%, and
(iii) the proportion by weight of component (c) is between 0% and 40%, the remaining constituents being water and other optional constituents selected from amongst those normally used in aqueous fabric-softening compositions.
Preferably, the aqueous fabric-softening compositions of the invention contain between 3% and 40% by weight of the total amount of components (a), (b) and (c) in a manner such that, with respect to the total amount of the said components (a), (b) and (c),
(i) the proportion by weight of component (a) is between 3% and 80%,
(ii) the proportion by weight of component (b) is between 0% and 97%, and
(iii) the proportion by weight of component (c) is between 0% and 30%, the remaining constituents being water and other optional constituents selected from amongst those usually used in aqueous fabric-softening compositions.
The cationic surfactants which are active as fabric-softeners and which constitute component (b) of the softening compositions of the invention are well-known to persons skilled in the art.
Amongst these may be mentioned. the quaternary ammonium compounds the hydrophobic chains of which are not interrupted by an ester group, for example, those described in the patents U.S. Pat. No. 4,719,382 and U.S. Pat. No. 4,237,016, amongst which the best known is hydrogenated tallow dialkyldimethylammonium chloride also known as DTDMAC as marketed by KAO Corporation, S.A. under the mark QUARTAMIN7 D86P.
However, the esterquats, descriptions of which, amongst many others, are to be found in the documents already cited in this description, which are incorporated herein by reference, are preferred and amongst those which may be mentioned as significant examples are the following:
X quatemized fatty-acid diesters with 1,2-dihydroxy-3-dimethylaminopropane, as described in U.S. Pat. No. 4,137,180 and European patent application EP-A-0585040,
X quaternized fatty-acid diesters with N-methyl diethanolamine, such as those described in French patent application FR-A-1593921 and in European patent EP-B-0239910, for example, hydrogenated tallow diester quaternized with methyl chloride, marketed by KAO Corporation, S.A. under the mark KAOSOFT7 PH,
X salts of fatty-acid amidoesters with N-methyl-N-aminopropyl ethanolamine, for example, that marketed by KAO Corporation under the mark KAOSOFT7 1,
X quaternized fatty-acid diesters with triethanolamine, such as those described in U.S. Pat. No. 3,915,867 and in a large number of subsequent patents, for example, diesters of partially hydrogenated tallow quaternized with dimethyl sulphate, which are marketed by KAO Corporation, S.A. under the marks TETRANYL7 AT-7590 and TETRANYL7 L1/90.
It should be pointed out that, when the term xe2x80x9cdiesterxe2x80x9d is referred to, it is intended to indicate that the diester is a major constituent of the mixture, although the product may still contain variable quantities of monoester compounds and, in the case of triethanolamine, of triester compounds.
Also included in this consideration of cationic surfactants of a softening nature are the oligomeric cationic surfactants described in patent application WO-A-9849132, for example, those marketed by KAO Corporation S.A. under the references TETRANYL7 PH-2 and TETRANYL7 PH-5.
The fabric-conditioning non-ionic surfactants which constitute component (c) are also well known to persons skilled in the art and amongst them may be mentioned: fatty acids, fatty-acid esters, particularly linear or branched C8-C18 fatty-acid esters, alkoxylated or without alkoxylation, Guerbet alcohols alkoxylated or without alkoxylation, glycerol esters, sorbitan esters alkoxylated or without alkoxylation, for example, KAOPAN7 marketed by KAO Corporation, S.A., sucrose esters, C8-18 fatty alcohols, glycerol esters, optionally alkoxylated, for example, LEVENOL7 marketed by KAO Corporation, S.A., and pentaerythritol esters, alkoxylated or without alkoxylation.
In so far as other optional components are referred to, although it should not be considered as an exhaustive description of all of the possibilities which, on the other hand, are well known to persons skilled in the art, the following may be mentioned:
a) Other products which improve the performance of the softening compositions, such as silicones, amine oxides, anionic surfactants such as lauryl ether sulphate or lauryl sulphate, amphoteric surfactants such as cocoamidopropyl betaine or the alkylbetaines, sulphosuccinates, polyglucosidate derivatives, etc.
b) Stabilizers such as salts of short-chain amines, quaternized or without quaternization, for example, of triethanolamine, N-methyl diethanolamine, etc., and also non-ionic surfactants such as ethoxylated fatty alcohols, ethoxylated fatty amines, ethoxylated alkylphenols, etc.
c) Products which improve viscosity control, for example, inorganic salts such as calcium chloride, magnesium chloride, calcium sulphate, sodium chloride, etc.; products which serve to reduce viscosity in concentrated compositions, such as glycol compounds, for example, ethylene glycol, dipropylene glycol, polyglycols, etc., and thickening agents for diluted compositions, for example, polymers derived from cellulose, guar gum, etc.
d) Components for adjusting the pH, which is preferably between 1.5 and 4.5, such as inorganic and/or organic acids of any type, for example, hydrochloric, sulphuric, phosphoric, and citric acids, etc.
e) Agents which improve xe2x80x9csoil releasexe2x80x9d, such as the known terephthalate-based polymers or copolymers.
f) Bactericidal preservatives such as formol, Kathon GC, Bronopol, etc.
g) Other products such as antioxidants, colouring substances, perfumes, germicides, fungicides, anticorrosive agents, anti-creasing agents, opacifiers, optical brightening agents, pearlizing agents, etc.
The softening compositions may be produced simply by mixing their constituents until they are dispersed or dissolved, with the use of methods well known to persons skilled in the art.